js 时间戳转换成几分钟前，几小时前，几天前

formatMsgTime (timespan) {  var dateTime = new Date(timespan);  var year = dateTime.getFullYear();  var month = dateTime.getMonth() + 1;  var day = dateTime.getDate();  var hour = dateTime.getHours();  var minute = dateTime.getMinutes();  var second = dateTime.getSeconds();  var now = new Date();  var now_new = Date.parse(now.toDateString());  //typescript转换写法  var milliseconds = 0;  var timeSpanStr;  milliseconds = now_new - timespan;  if (milliseconds <= 1000 * 60 * 1) {    timeSpanStr = '刚刚';  }  else if (1000 * 60 * 1 < milliseconds && milliseconds <= 1000 * 60 * 60) {    timeSpanStr = Math.round((milliseconds / (1000 * 60))) + '分钟前';  }  else if (1000 * 60 * 60 * 1 < milliseconds && milliseconds <= 1000 * 60 * 60 * 24) {    timeSpanStr = Math.round(milliseconds / (1000 * 60 * 60)) + '小时前';  }  else if (1000 * 60 * 60 * 24 < milliseconds && milliseconds <= 1000 * 60 * 60 * 24 * 15) {    timeSpanStr = Math.round(milliseconds / (1000 * 60 * 60 * 24)) + '天前';  }  else if (milliseconds > 1000 * 60 * 60 * 24 * 15 && year == now.getFullYear()) {    timeSpanStr = month + '-' + day + ' ' + hour + ':' + minute;  } else {    timeSpanStr = year + '-' + month + '-' + day + ' ' + hour + ':' + minute;  }  return timeSpanStr;};